Days before School of Seven Bells even set foot in Tampa, the fan buzz was about anything but their music.

Claudia Deheza, twin sister of lead singer Alejandra, was nowhere to be found, having taken leave of her sibling and former Secret Machines guitarist Benjamin Curtis somewhere between California and Ybor City. Only cryptic postings on the New York band's Facebook fan page and Twitter feed, @sviib, gave any clues.

"Hi everybody. We just wanted to let you all know that Claudia has left the band for personal reasons," the postings read Tuesday, addressing concerns that Claudia had taken ill. "In the meantime, we are excited to continue to write and tour as usual, and we're very much looking forward to seeing you all at our upcoming shows. ♥ Alley and Benjamin"

I'd wanted to see them live since hearing Prefuse 73's Class of 73 Bells (a remix of Iamundernodisguise, a cut from 2008's Alpinisms), so the news was a bit of a shock. Would the Deheza twins' signature, ethereal harmonizing be at all intact with part of the equation missing? Not to worry, Curtis assured me via Twitter.

"can't speak for claudia's personal reasoning behind her decision...," he wrote when I asked for comment in advance of Thursday's show at Crowbar. "the music is written by A & I, with A singing most of the record's vocals&harms, it's sad but more like losing a touring member and touring just wasn't for her"

Touring may not have been for Claudia, but it seems to agree with Alejandra and Benjamin quite well, even if some critics think July's new Disconnect From Desire isn't quite the jaw-dropping achievement Alpinisms was. Let's amend that: It may not be as empyrean as Alpinisms, but it certainly is more mature, more the product of accomplished musicians. Alejandra's opening of the set with Half Asleep showed Claudia's backing vocals could have helped the live performance stay album-quality, but it also did something better: It showed SVIIB is growing.

Whether through faulty equipment at Crowbar -- Benjamin's microphone was cutting out, for one thing, just as it did for opening acts Sleepy Vikings, from Tampa, and L.A.'s Active Child -- or nerves over performing the last few days without Claudia, the group shuffled through cuts Heart Is Strange, Babelonia, Joviann and Dust Devil before toning down overlayered and largely unnecessary vocal effects.

Perhaps it was simply an on-the-fly adjustment, but Alejandra was at her best when allowed to showcase more of her raw voice, so by the time they dug into Bye Bye Bye, the Bells had found their groove. An audience enthusiastic enough to show up during a Tampa Bay musical week featuring Vampire Weekend, Flaming Lips, GWAR, Stone Temple Pilots and even the Bush reunion tour (which was down the street at Ritz Ybor the very same night) heartily agreed.

Curtis' guitar playing prowess is much more apparent onstage than it is in the earbuds; Windstorm's melodic showcase proved that Disconnect From Desire highlights a band that seems to be moving from electronic overdependence to strong outright musical theory. This is a good thing. Their very able and energetic touring drummer, Zach Saginaw, certainly helped. My only wish is that they had played Chain, the song Adult Swim pimped out a couple years back to help catapult them into more mainstream awareness, but that's just me being nerdy.

After I L U and My Cabal, Bells gave a rousing rendition of Sempiternal/Aramanth as the encore, Deheza's vocals plowing through heavy drums and feedback for nearly 10 minutes to prove that Alejandra and Benjamin will go on despite the loss of their third member. But even better, they showed that the path they're on can only go uphill.